뒤로Anatomy of the Newborn Skull: Fontanelles and Cranial Bones
스터디 가이드 - 스마트 노트
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Skull Anatomy of the Newborn
Overview of the Newborn Skull
The skull of a newborn is composed of several bones joined by connective tissue regions called fontanelles. These soft spots allow for flexibility during birth and accommodate rapid brain growth in infancy. The major bones and fontanelles are visible from both superior and lateral views.
Frontal bone: Forms the forehead and the upper part of the eye sockets.
Parietal bones: Paired bones forming the sides and roof of the cranium.
Occipital bone: Forms the back and base of the skull.
Temporal bone (squamous portion): Located at the sides and base of the skull.
Fontanelles of the Newborn Skull
Fontanelles are membranous gaps between the cranial bones in infants. They are crucial for skull flexibility and brain development. There are four main fontanelles:
Anterior fontanelle: Located at the junction of the frontal and parietal bones, this is the largest fontanelle and is diamond-shaped. It typically closes by 18-24 months of age.
Posterior fontanelle: Found at the junction of the parietal and occipital bones, this smaller, triangular fontanelle usually closes by 2-3 months of age.
Sphenoidal (anterolateral) fontanelle: Located at the junction of the frontal, parietal, temporal, and sphenoid bones. It closes by about 6 months of age.
Mastoid (posterolateral) fontanelle: Found at the junction of the parietal, occipital, and temporal bones. It also closes by about 6-18 months of age.
Key Points about Fontanelles
Function: Allow for molding of the skull during birth and accommodate rapid brain growth.
Clinical significance: Palpation of fontanelles can provide information about hydration status and intracranial pressure in infants.
Closure timeline: Each fontanelle closes at a different age, which is important for normal skull and brain development.
Cranial Sutures
Sutures are fibrous joints that connect the bones of the skull. In newborns, these sutures are wide and flexible, but they gradually ossify with age.
Frontal suture: Runs between the two halves of the frontal bone (may persist as the metopic suture in some adults).
Other major sutures: Sagittal (between parietal bones), coronal (between frontal and parietal bones), and lambdoid (between parietal and occipital bones).
Table: Major Fontanelles of the Newborn Skull
Fontanelle | Location | Shape | Approximate Closure Age |
|---|---|---|---|
Anterior | Junction of frontal and parietal bones | Diamond | 18-24 months |
Posterior | Junction of parietal and occipital bones | Triangular | 2-3 months |
Sphenoidal (Anterolateral) | Junction of frontal, parietal, temporal, sphenoid bones | Irregular | 6 months |
Mastoid (Posterolateral) | Junction of parietal, occipital, temporal bones | Irregular | 6-18 months |
Clinical Application
Bulging fontanelle: May indicate increased intracranial pressure.
Sunken fontanelle: May suggest dehydration.
Delayed closure: Can be associated with certain medical conditions such as hypothyroidism or increased intracranial pressure.
Summary
The newborn skull is characterized by the presence of fontanelles and flexible sutures, which are essential for birth and brain growth.
Understanding the anatomy and closure timeline of fontanelles is important for assessing infant health and development.
